N-Acetyl DSIP

1 Identity

Synthetic nonapeptide, N-terminally acetylated. Linear, unmodified backbone, all proteinogenic L-residues, no cysteine and therefore no disulfide, no lipid, no PEG, no metal. The parent is DSIP (WAGGDASGE), INN emideltide, CAS 62568-57-4. 'N-Acetyl DSIP' is not a synonym for DSIP, not a synonym for emideltide, and not a synonym for N-acetyl DSIP amide - three separate articles that this shelf routinely conflates. The canonical name contains the phrase 'sleep-inducing'.

Sequence

Ac-Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu-OH - the sequence WAGGDASGE bearing a single acetyl group on the tryptophan alpha-amine. Nine residues; free C-terminal carboxylic acid, not amidated. No D-residues, no non-proteinogenic residues, no cysteine, no disulfide, no acylation beyond the N-terminal acetyl. No basic residue is present anywhere in the chain and the only amine in the molecule is capped, so the article carries essentially no trifluoroacetate; the counterion question is sodium on the Asp5 and Glu9 carboxylates and is answered per lot rather than assumed. One structural feature governs the whole specification: the Asp5-Ala6 junction is aspartimide-prone.

Molecular formula

C37H50N10O16 (free acid, salt-free). Parent DSIP is C35H48N10O15; N-terminal acetylation is exactly +C2H2O.

Average mass

890.861 Da, from C37H50N10O16 on IUPAC 2021 abridged conventional atomic weights (C 12.011, H 1.008, N 14.007, O 15.999). The figure 890.85 is what the pre-2021 table (C 12.0107, H 1.00794, N 14.0067, O 15.9994) returns for the identical formula: 890.850. Both are arithmetically correct on their own basis; the catalog standardizes on the 2021 table and prints the basis. The delta from the parent is +42.037 average.

Monoisotopic mass

890.3406 Da neutral monoisotopic for C37H50N10O16. [M+H]+ 891.3479; [M+2H]2+ 446.1776; [M-H]- 889.3333. The delta from the parent DSIP monoisotopic 848.3301 is exactly +42.0106, the acetyl increment.

Salt / variant note

The substitution and isomer risks around this article are larger than the usual case. (1) Unacetylated DSIP, WAGGDASGE, C35H48N10O15, avg 848.824 / mono 848.3301, exactly -42.011 average and -42.0106 monoisotopic. Catalogued under CAS 62568-57-4 as the trifluoroacetate salt. The substitution is trivially detectable: [M+H]+ 891.35 is the acetylated peptide, 849.34 is not. (2) The beta-aspartyl (isoaspartyl) isomer at Asp5, produced by aspartimide ring-opening during Fmoc synthesis and on storage. The parent's isomer is sold as its own catalog article - '(beta-Asp5)-Delta-Sleep Inducing Peptide', CAS 82602-88-8 - with formula C35H48N10O15 and MW 848.82, character for character identical to the parent's. The acetylated counterpart, Ac-(beta-Asp5)-DSIP, is C37H50N10O16, avg 890.861 / mono 890.3406 - exactly isobaric with the product at any resolving power. This isomer is real, common and expensive to exclude. (3) N-acetyl DSIP C-terminal amide, C37H51N11O15, avg 889.877 / mono 889.3566, -0.984 Da from the product and invisible on a unit-resolution quadrupole. (4) DSIP C-terminal amide, C35H49N11O14, avg 847.843 / mono 847.3460. (5) Phosphorylated DSIP (Ser7 phosphate, CAS 70754-23-3), itself a catalogued reagent, C35H49N10O18P, avg 928.795 / mono 928.2964, +79.966 from the parent; derived by adding HPO3 to the parent formula, with the phosphorylation site to be confirmed by MS/MS rather than assumed. (6) The D-Asp5 epimer of the acetylated peptide, generated by the same aspartimide ring-opening: identical formula, identical average and monoisotopic mass, invisible to every achiral method. (7) Chain-length substitutions from the same synthesis: des-Glu9 DSIP(1-8) C30H41N9O12 avg 719.706 / mono 719.2875, and des-Trp1 DSIP(2-9) C24H38N8O14 avg 662.607 / mono 662.2507.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and is thin and old, and this record says so rather than dressing it up. Foundational isolation and characterization of the parent: Schoenenberger GA, Monnier M, Proc Natl Acad Sci USA 1977;74:1282-1286, from rabbit cerebral venous blood. The animal literature that followed through the 1980s is largely rabbit and rat electroencephalography; the human literature of the same period consists of small open-label and crossover studies, mostly European, with subject counts in the single and low double digits and no modern replication. No receptor was ever identified for DSIP, which is a substantive gap in the record rather than a stylistic one. For the N-acetyl derivative specifically the literature is thinner again: a small number of stability and pharmacokinetic comparisons against the unacetylated peptide, and no controlled human trial of the acetylated form was identified. No registered studies under either identity are listed on ClinicalTrials.gov.

4 Storage & specification

Storage

Lyophilized white to off-white solid. -20 degrees C plus or minus 5 degrees C, desiccated over silica, protected from light because of Trp1, sealed under inert headspace in Type I amber glass, stoppered and crimped. Equilibrate the sealed vial to room temperature before opening. Short excursions to 2 to 8 degrees C during shipping are acceptable and are bounded by the excursion arm of the stability study; single-use temperature logger in every export carton. The material must not be stored reconstituted, and both the vial label and the certificate say so.

Shelf life

Provisional 24-month retest interval at -20 degrees C plus or minus 5 degrees C, desiccated and light-protected. The confirming study is an ICH Q1A(R2) design with the isoaspartyl impurity as the stability-indicating attribute, alongside total related substances, tryptophan oxidation products and water: timepoints 0, 3, 6, 9, 12, 18 and 24 months at -20 degrees C, with 2 to 8 degrees C and 25 degrees C / 60 percent RH arms. If the isoAsp limit is approached before 24 months the interval shortens. This is the retest date printed on the label, and it moves with the data.